Cite this post as:
Guest Author. Inspiratory IVC Collapse: some physiological considerations by Jon-Emile Kenny. EMCrit Blog. Published on July 14, 2017. Accessed on March 29th 2024. Available at [https://emcrit.org/emcrit/physio-ivc-collapse/ ].
Financial Disclosures:
Dr. Scott Weingart, Course Director, reports no relevant financial relationships with ineligible companies.
This episode’s speaker(s), (listed above), report no relevant financial relationships with ineligible companies.
CME Review
Original Release: July 14, 2017
Date of Most Recent Review: Jan 1, 2022
Termination Date: Jan 1, 2025
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Dr Kenny, Your animation does an excellent job in highly the complexity of the IVC collapse (or distension) with multiple factors influencing this “pseudo-parameter”. What interests me is the physiology behind IVC collapse (or distension) rather than the sensitivity or specificity of this “pseudo-parameter” and how this relates to bi-ventricular preload dependency (or not). We all understand (hopefully) the elegance of the physiology behind pulse pressure variation (PPV), and stroke volume variation (SVV) is the sedated patient receiving 8mls/kg positive breaths (i.e in the operating room). Similarly, the physiology behind the passive-leg raising (PLR) maneuver) in determining bi-ventricular preload dependency… Read more »
Hi Dr. Marik. Thank you for your question; it is an excellent question. The relationship is complex, difficult to describe with words and probably best understood using the Guyton Diagram. The animation that I used in the vodcast above is, essentially, a cartoon of Guytonian physiology. The right atrial pressure is formed by the intersection of venous return and cardiac function. Because the right atrial pressure lies at the cross-roads of venous return and cardiac function, the value itself cannot tell us anything definitive about the slope of the cardiac function curve [volume responsiveness] or venous return [partially determined by… Read more »
I like the idea of considering two different physiological issues going on here. To that end could you not consider them individually to guide your treatment decisions? What about comparing RV volume to LV volume to decide if it’s a pump issue. What about considering the slope of the a and v lines of the CVP to reflect the capacitance of the venous system (steeper slopes = more unstressed being converted to stressed). The idea that any one parameter can accurately reflect the function of a multi system problem is what gets us in to trouble. I love this recent… Read more »
I would also like to point out that I still have a hard time rationalizing the idea of giving tremendous amounts of fluids to a patient that hasn’t necessarily lost tremendous amounts of fluid. Just like we have decided that filling hemorrhage patients with blood is better than saline I don’t understand how we think the best way to treat profound vasopalegia is to fill to tank more until we get a pressure that we like. Insensible loss increases from sepsis aside, it’s seems hugely obvious to me that a better way to go would be to convert that vasoplegic… Read more »
You hit the Jackpot.
Thanks so much for your comments and your suggestions. I think that you sum it up perfectly when you say: “The idea that any one parameter can accurately reflect the function of a multi system problem is what gets us in to trouble.” Yeup. I try to look at it simply; you have to test the question that you are asking. If you desire to know if the heart is fluid responsive, you have to 1. augment its preload and 2. rapidly determine if it’s increasing its output in response; for example a passive leg raise with doppler velocity measurement.… Read more »